Diesel fuel



Patented Aug. 3, 1 943 UNITED STATE s PATENT orrlca nmsanr'unn Edwin M-Nmamna John H. McCracken,

Woodbury, and Francis M. Sager; Pitman, N. 1., assignors toSocony-Vacuum Oilv Company, In

corporated, New York New York, N. Y., a corporation of No Drawing.Application April 24, 1941,

Serial No. 390,102

13 Claims. (01. 44-51) This invention has to do in a general way withportant to the attainment of maximum efficiency that the delay periodbetween injection and ignition be short. Improperly delayed ignition in2.

Diesel engine gives rise to the phenomenon known as knocking, which isdue to improper coordination of combustion and cylinder conditions. Byaccelerating the-ignition of Diesel fuel, it is possible to lower thecompression pressure. This insures spontaneous ignition withoutcombustion shock, thereby increasing the ease of starting and thesmoothness with which combustion Also, the low compression prestakesplace. sure permits less weight in the engine and a lower cost per givenpower output. It is obvious,

' therefore, that enhanced speed of ignition is a characteristic whichis highly desirable in a Diesel fuel.

It has been found that the ignition quality of the fuel oils normallyclassified as Diesel fuels can be improved by the addition of smallamolmts of certain compounds which will act as ignition accelerators,thereby decr'easingthe ignition delay period. This offers a means forimproving the better grades of Diesel fuels and a means for widening therange of available fuels by raising the ignition quality of the lowergrades to a point where they can be 'satisfactorily used.

This invention'is predicated upon the discovery that Diesel fuels ofimproved ignition quality can be obtained by admixing with the' fuel aminor proportion of the compound or reaction product obtained byreacting perchloro methylmercaptan (ChQSCD with a compound ofthe generalformula R('XH)1. or R(XM)1I,

. where IR. represents an alkyl, aryl, alkaryl, or

' aralkyl radical and X isjoxygen or sulfur and M represents thehydrogen equivalent of a metal and 1; is a whole number.

\- Perchloromethylmercaptan, as indicated by the formula above,. is achlorinated substituted examples:

sulfur chloride and can be prepared by the chlorination of carbondisulflde according to the method of Helfrich and Reid (Jour. Amer.

Chem. Soc. 43, 591 (1921)). For example, carbon disulflde containingabout .4 per cent by weight of iodine was chlorinated in the absence ofdirect sunlight at a temperature maintained hols (including mercaptans)and phenols (ineluding thiophenols) and the corresponding metalderivatives, (alcoholates, phenolates, mer captides, etc). To facilitatethe reaction of the perchloromethylmercaptan and a: secondary reactantRXH, it is desirable to carry out the reaction in the presence of analkali metal or its corresponding hydroxide; and when the reaction iscarried out in this-way, the metal may be present as a-substituentreplacing the hydrogen in the KB": group of the secondary reactant andin such an instance, even though the compound used as the secondaryreactant has the general formula RXH, the compound actually enteringinto the reaction has the formula'RXM.

Typical procedures which may be employed in synthesizing the reactionproducts contemplated herein are illustrated by the following Emu: I

ifreparation of reaction, product between perchlormnethylmercaptan andphenol dition. After 15, minutes an oil was extracted with 5.1 parts ofether, the ether extract washed.

twice with water and dried over anhydrous potassium carbonate. The etherextract was filtered into a distilling flask and the ether re-Preparation of reaction product obtained jfrbm perchloromethylmercaptanand ethyl alcohol To 14.5 parts of absolute ethyl alcohol contained in a2-liter three-necked flask equipped with a Hershberg 'wire stirrer andreflux condenser was added 1 part of metallic sodium, The

mixture was cooled to control the reaction.

When most of the sodium had dissolved, the reaction flask was surroundedwith. an ice bath and to the cold mixture was slowly added over a periodof a half an hour 6.3 parts of perchloromethylmerca'ptan dissolved in19.7 parts of petroleum ether. A white precipitate formed immediately.To the product was added 45.5 parts of water, which dissolvedtheprecipitate. The aqueous layer was extracted with an additional 50cc. (2.3 parts) of petroleum ether. The petroleum ether extracts werecombined, washed with water, dried over calcium chloride, and filteredinto a distillingfiask. The contents of the flask were heated to 50 C.under vacuum to completely remove the petroleum ether. The yield ofcrude product was 139 grams (6.3 parts).

The examples given above are merely illustrative, and from them themodifications necessary to synthesize reaction products from othercompounds within the class typified by the formula RXH will readilyappear to those skilled in the art. Other typical compounds which arecontemplated for use as the secondary reactant are substituted phenols,such as cresols, trinitrophenol, xylenols, naphthols, etc., thiophenoland substituted thiophenols, such as thiocresols, thioxylenols, etc.,aliphatic alcohols in general, including monohydric and polyhydricalcohols To demonstrate the effectiveness of the reaction productscontemplated herein as improving agents for Diesel fuels, blendsoftypical reactidn products were prepared in a straight-rim Num-' her 2fuel oil, and the cetane numbers of the blends were obtained forcomparison with the cetane number of the blank'fuel oil. The cetanenumbers were determined by the proposed method of the A. S. T. M. (A. S.T. M. Proc. 38 I 392 (1938)). The fuel oil used had the followincharacteristics:

Gravity, A. P. I 39.8 Flash point (Pensky-Martens F.) 1'72 Anilinepoint, 160.5 A. S. T. M. distillation:

Initial "F 386 10% 435 90% 572 End point -1 614 Diesel index 63.9 CetaneN 55 (glycol, glycerol, etc.) f substituted alcohols, such I as nitroalcohols, etc., and aliphatic and aralkyl mercaptans in general,including mono-, di-, and tri-, mercaptans, benzyl mercaptans,thioglycols, etc., and the metal derivatives (alcoholates, phenolates,and mercaptides) corresponding to the foregoing compounds.

Reactlon products have been prepared and tested and found satisfactoryas ignition accelerators for Diesel fuels wherein the secondary reactantwas selected from the group consisting of phenol, ethyl alcohol, amylmercaptan, tertiary butyl mercaptan, thiophenol, and benzyl mercaptan.-In the class of compounds contemplated herein as secondary reactants,preference is given to phenols, mercaptans and thiophenols. The exactchemical composition of the reaction products contemplated herein isuncertain, but they contain substantial quantities of chlorine andsulfur derived from the perchloromethyl mercaptan, ClaCSCl. .They areprobably predominantly comprised of compounds having the generalformulae ClaC-SS-R or ClaC- S-OR, depending upon whether the secondaryreactant is a. inercaptan (o'r mercaptide) or an alcohol (oralcoholate). Because of the uncertainty as to the exact chemicalcomposition of-these products, they are defined hereinfby'the method ofpreparation.

The term Diesel fuel, as used herein, has referenceto'those non-viscouspetroleum fractions commonly denoted in the art as Diesel fuels and tothose hydrocarbon products in? general whose physical characteristicsrender 'them suitable for use in compression ignition engines.

-tain specific procedures and have referred to various specificcompounds as the secondary re-' actants, our invention is not limitedthereto but The cetane number determinations and the extent to which thecetane numbers were improved by the various reaction products ar shownin Table I below.

TABLE I Substance blended with 55 octane Per cent Cetane Increase by wtN o. of in cetone numb" added blend No.

Reaction product obtained from perchloromethylmercaptan withhenol 1. 060. 5 5. Do 1. 0 62. 0 7. Ethyl alcohol 1.0 58.0 3. Amy] mereaptan l. 062. 0 7. E l. 0 58. 0 3. Tertiary butyl mercapta 1.0 62. 0 7.Thio-phenoL. i. 0 6i. 6 6. Benzyl mercaptan. l. 0 61. 6 6.

The reaction products obtained from perchloromethylmercaptan withthio-phenol and benzyl mercaptan were also added to a catalyticallycracked Number 2 fuel oil, and the cetane number of the blends weredetermined. The

base fuel has the following characteristics:

' Gravity, A. P. I 28.8 Flash pointv (Pensky-Martens F.) 200 Anilinepoint, F 122 -A. S. T. M. distillation:

Initial "F 431 10% 467 582 End point 629 Diesel index 35.1

Cetane number 33.0

The cetane number determinations are listed in Table II below.

The reaction products contemplated herein maybe'used in amounts rangingfrom about 0.1

per cent to about 5.0-per cent; and it is to be understood that althoughwe have described cermodifications are fairly encompassed by theappended claims.

We claim:

1. An improved Diesel fuel comprising a hydrocarbon fuel oil andinadmixture therewith a minor. proportion of the oil-miscible productobtained by first reacting perchloromethylmercaptan with a compoundselected from the group consisting of compounds having the generalformula ROG-I) and R (XM)n, wherein R. is selected from the groupconsisting of alkyl, aryl, alkaryland aralkyl radicals, X is selectedfrom the group consisting'o'f oxygen and sulfur, .M'is a metal, and n isa whole number, and then separating the oil-miscible reaction productfrom the unreacted and oil-immiscible components of the reactionmixture, said oil-miscible reaction product being characterized by thepresence of a group selected from the group consisting of uct from theunreacted and oil-immiscible com-- ponents in the reaction mixture bywater-washing and extracting with an organic solvent, said oil-misciblereaction product being characterized by the presence of group consistingof and ns-H groups.

3. An improved Diesel fuel comprising a hydrocarbon fuel oil and inadmixture therewith a minor proportion of the oil-miscible productobtained by first reacting perchloromethylmera group selected from theimmiscible components of the reaction mixture.

6. An improved Diesel fuel comprising a nonviscous petroleum oil and inadmixture therewith a minor proportion of the oil-miscible productobtained by first reacting perchloromethylmercaptan with a phenol andthen separating action product from the unreacted and oil-immisciblecomponents of the reaction mixture, said reaction product being presentin an amount sufficient to decrease the ignition delay period of thefuel.

'8. An improved Diesel fuel comprising a nonviscous petroleum oil and inadmixture therewith a minor proportion of the oil-miscible productobtained byfirst reacting perchloromethylmercaptan with a thiophenol andthen separating said reaction product from the unreacted andoil-immiscible components of the reaction mixture, said reaction productbeing present in an amount sufficient to decrease the ignition delayperiod of the fuel.

9. An improved Diesel fuel comprising a nonviscous petroleum oil and inadmixture therewith a minor proportion of the oil-miscible productobtained by first reacting perchloromethylmercaptan with a compoundselected from the group consisting of phenol, thiophenol, benzylmercaptan, ethyl alcohol, amyl mercaptan, and

tertiary butyl mercaptan and then separatingsaid reaction product fromthe oil-immiscible and unreacted components in. the reaction mixture,said reaction product being present in an amount sufiicient to decreasethe ignition delay period of the fuel.

captan with a phenol, and then separating said reaction product from theunreacted and the oil-immiscible components in the reaction mixture.

4. An improved D1esel fuel comprising a hydrocarbon fuel oil and inadmixture therewith a minor proportion of the oil-miscible productobtained by first reacting .perchloromethylmercaptan with a mercaptanother than perchloromethylmercaptan, and then separating said reactionproduct from the unreacted and oil-immiscible components in the reactionmixture.

5. An improved Diesel fuel comprising a' hydrocarbon fuelpoil andinadmixture therewith a minor proportion of the oil-miscible productobtained by first reacting perchloromethylmercaptan with thiophenol, andthen separating'said 10. An improved Diesel fuel comprising ahydrocarbon fuel oil and in admixture therewith a minor proportion ofthe oil-miscibleproduct obtained by first reactingperchloromethylmercaptan with a compound selected from the groupconsisting of phenol, thiophenol, benzyl mercapconsisting of phenol,thiophenol, benzyl mercaptan, ethyl alcohol, amyl mercaptan, andtertiary butyl mercaptan, and then separating said reaction product fromthe unreacted and oil-immiscible components of said reaction mixture.

12. An improved Diesel fuel comprising a hydroc'arbon fuel oil and inadmixture therewith a minor proportion of the reaction product obtainedby interreacting phenol with perchlorohydroxide solution; extracting thereaction prodmethyl mercaptan in the presence of an alkali reactionproduct from the unreacted and oil-' distilling the ether extract toobtain said reaction product. i

13. An improved Diesel fuel comprising a hy-- drocarbon fuel oil and inadmixture therewith a minor proportion oi! the reaction productobtamedby interreacting anethyl alcohol solution of metallic sodium withperchloromethyl mer-

